1. Field of the Invention
This invention relates to an apparatus for sedimentation through centrifugation and, more particularly to an apparatus and method for creating at least one acoustic standing wave oriented generally orthogonal to the direction of the centrifugal force to provide enhanced sedimentation during centrifugation.
2. The Prior Art
Centrifugation apparatus are well known in a fluid material in the art and include devices for creating substantial centrifugal forces by rapidly spinning a quantity of the fluid material about an axis. The centrifugal force imposed upon particles or fractions in the fluid having different densities is proportional to the size and density of the particles as compared to the density of the fluid, the rate of rotation and the radial distance from the axis of rotation. These forces are stated in terms of gravity (G) so that a high speed centrifuge apparatus will create forces in the range of thousands of G's. However, even in the presence of such relatively strong centrifugal force fields certain particles require extensive periods of centrifugation to achieve the desired degree of separation.
One of the problems with centrifugation is that certain fluids may include a suspension of very fine particles having a density nearly identical to the fluid. The centrifugal forces created by the centrifuge apparatus act on these very slight density differences so that only a small fraction of the available centrifugal force is effective in moving the particle through the fluid.
Further, in order to move a particle through the fluid the particle must displace fluid in the opposite direction in order to achieve relative movement. Both of these factors are operative when a fluid such as blood is subjected to centrifugation. It has also been determined that agglomerated particles have a significantly greater rate of sedimentation under even a reduced centrifugal force.
It would, therefore, be a significant advancement in the art to provide an apparatus and method whereby particles in the fluid could be agglomerated so as to increase the rate of sedimentation during centrifugation. An even further advancement in the art would be to provide an apparatus and method for agglomerating particles in the fluid undergoing sedimentation, the agglomerated particles being formed in one or more bands generally orthogonal to the centrifugal forces so as to provide channels for the movement of displaced supernatant as the particles are sedimented. Such a novel apparatus and method is disclosed and claimed herein.